Metals are obtained from compounds containing them by processes, such as electrolysis (in aqueous solution or in a melt) aluminothermal reduction, reduction by alkali metal or alkaline earth metal, and reduction (of the metal oxide or hydroxide) with carbon or hydrogen. Hydroxides of, for example, iron, cobalt, nickel, germanium, molybdenum, ruthenium, tungsten, rhenium and osmium are reduced to their respective metals with hydrogen.
The treatment with hydrogen of oxides (or hydroxides) of metals of the first and second main groups or the third, fourth and fifth subgroups of the Periodic Table of Elements, however, does not lead to reduction to the metal. A series of metals, including lithium, calcium, strontium, and barium are derived from their respective halogen salts by melt electrolysis. Reducing oxides (or hydroxides) of these metals with hydrogen has thus far not been possible.
Hydrogen reduction of actinide base metals, such as americium, californium and curium, is not known. Americium is obtained by reduction of americium trifluoride with lithium, barium, lanthanum or thorium at 1100.degree. to 1200.degree. C.
Separation of metals from one another has thus far been effected either during processing of ores containing the metals (virtually always requiring subsequent cleansing), by electrolysis, or via the detour of preparing inorganic or organic compounds of the metals with subsequent separation of the compounds from one another and conversion of the individual compounds into respective metals.
Preparation of intermetallic compounds is usually effected by melting pure metals together. Only a relatively small number of intermetallic compounds with a high proportion of the more noble metal has been obtained by hydrogen reduction from oxides (or hydroxides) of lithium, aluminum, scandium, yttrium, silicon, titanium, vanadium, niobium, tantalum, chromium, from rare earth metal oxides or from alkaline earth oxides, respectively, with platinum also with rhodium, palladium and iridium in the case of titanium and with palladium in the case of silicon (H. Schulz, K. Ritapal, W. Bronger, W. Klemm "Ueber die Reaktion von Elementen der achten Nebengruppe mit Oxiden unedler Metalle im Wasserstoffstrom" [The Reaction of Elements of the Eighth Subgroup with Oxides of Base Metals in a Stream of Hydrogen] Magazine for inorganic and general chemistry, volume 357, 1968, pages 299-313), (W. Bronger, W. Klemm, "Darstellung von Legierungen des Platins mit unedlen Metallen" [Obtaining Platinum Alloys with Base Metals], Magazine for inorganic and general chemistry, volume 319, 1962/63, pages 58-81) and (W. Bronger "Preparation and X-Ray Investigation of Platinum Alloys with the Rare-Earth Metals [Pt.sub.5 Ln and Pt.sub.3 Ln-Phases]", Journal of the Less Common Metals, volume 12, 1967, pages 63-68). The described intermetallic compounds are listed in the following Table 1:
TABLE 1 ______________________________________ Intermetallic Reduction Temperature Compound (.+-. 50).degree. C Type of Structure ______________________________________ Pt.sub.7 Li 1000 Pt.sub.7 Mg Pt.sub.3 Mg 1150 Cu.sub.3 Au Pt.sub.3 Al 1200 Cu.sub.3 Au Pd.sub.2 Si 1100 Fe.sub.2 P Pt.sub.2 Ca 1200 Cu.sub.2 Mg Pt.sub.5 Ca 1200 Cu.sub.5 Ca Pt.sub.3 Sc 1200 Cu.sub.3 Au Pt.sub.3 Ti 1200 Cu.sub.3 Au Pd.sub.3 Ti 1200 Ni.sub.3 Ti (hex.) Ir.sub.3 Ti 1550 Cu.sub.3 Au Rh.sub.3 Ti 1550 Cu.sub.3 Au Pt.sub.3 V 1000 Al.sub.3 Ti Pt.sub.3 Cr 1000 Cu.sub.3 Au Pt.sub.2 Sr 1200 Cu.sub.2 Mg Pt.sub.3 Sr 1200 unknown Pt.sub.5 Sr 1200 Cu.sub.5 Ca Pt.sub.5 Y 1200 Pt.sub.5 Tb Pt.sub.3 Nb 1200 Cu.sub.3 Ti Pt.sub.2 Ba 1200 Cu.sub.2 Mg Pt.sub.5 Ba 1200 Cu.sub.5 Ca Pt.sub.3 Ho 1200 Cu.sub.3 Au Pt.sub.3 Er 1200 Cu.sub.3 Au Pt.sub.3 Tm 1200 Cu.sub.3 Au Pt.sub.3 Yb 1200 Cu.sub.3 Au Pt.sub.3 Lu 1200 Cu.sub.3 Au Pt.sub.5 La 1200 Cu.sub.5 Ca (hex.) Pt.sub.5 Ce 1200 Cu.sub.5 Ca (hex.) Pt.sub.5 Pr 1200 Cu.sub.5 Ca (hex.) Pt.sub.5 Nd 1200 Cu.sub.5 Ca (hex.) Pt.sub.5 Sm 1300 Pt.sub.5 Eu 1300 Pt.sub.5 Sm Pt.sub.5 Gd 1200 Pt.sub.5 Sm Pt.sub.5 Tb 1200 Pt.sub.5 Dy 1200 Pt.sub.5 Tb Pt.sub.5 Ho 1200 Pt.sub.5 Tb Pt.sub.5 Er 1200 Pt.sub.5 Tb Pt.sub.5 Tm 1200 Pt.sub.3 Ta 1200 Cu.sub.3 Ti ______________________________________
The authors, W. Bronger et al, called this hydrogen reduction of metal oxides (or hydroxides) which leads to intermetallic compounds a "coupled reduction".
Intermetallic compounds of the actinide metals: thorium, uranium and plutonium, with rhodium, palladium, iridium and platinum have been described (A. E. Dwight el al, "Acta Crystallographica", Vol. 14, pages 75 and 76, 1961, and V. I. Kutaitsev et al, "Soviet Atomic Energy", Vol. 23, pages 1279 to 1287, 1967). To produce such binary compounds, the metals are melted together in very pure form in an electric arc. However, intermetallic compounds, or alloy phases or mixtures of intermetallic compounds and alloy phases of the actinides: protactinium, neptunium, americium, curium and californium, with metals of the eighth subgroup of the Periodic Table of elements, e.g. rhodium, palladium, iridium and platinum, are not known.